A bone cement composition has heretofore been widely used in the world as a bone prosthetic material for a defective part of a bone or an adhesive for fixing a metallic prosthesis such as a hip joint prosthesis to its surrounding bones. A polymethyl methacrylate (PMMA)-based bone cement composition has been most commonly used as such a bone cement composition.
The PMMA-based bone cement composition generally contains polymethyl methacrylate, a methyl methacrylate monomer that is a polymerizable monomer, and a polymerization initiator. The methyl methacrylate monomer is polymerized in the presence of polymethyl methacrylate, whereby the viscosity of the composition is gradually increased to finally form a hardened material.
A PMMA-based bone cement composition heretofore used as the PMMA-based bone cement composition has biocompatibility, but does not have bioactivity, i.e., bone-bonding ability to be bonded to a bone, so that when the composition is used as an adhesive for fixing a prosthesis to its surrounding bones in particular, the adhesive separates from the surrounding bones when a long period of time has elapsed from the application thereof, resulting in causing a problem that looseness occurs between the prosthesis and the bones. In order to solve this problem, in recent years, there has been proposed a composition with titanium dioxide particles added thereto for the purpose of imparting the bioactivity thereto (see, for example, Patent Literature 1).
Such a bone cement composition is generally used by for example, causing a polymerization reaction of the methyl methacrylate monomer to start by kneading it just before its application during a surgical operation or the like and applying the kneaded product to a site to be applied by a handling operation at the time the viscosity of the kneaded product has been increased by the process of leaving the kneaded product to a certain extent.
However, the bone cement composition heretofore used involves a problem that such evils that the kneaded product adheres to, for example, surgical gloves made from a latex, which have been put on hands, during the above-described handling operation in a surgical operation in particular in many cases occur.
Such a problem is caused by the fact that the handling operation is started before the kneaded product of the bone cement composition comes to have a sufficient viscosity, so that it is required to shorten a time necessary for the kneaded product to have a sufficient viscosity required to conduct a good handling operation, said time being called “doughing time”. When a filler such as titanium dioxide particles is added to the composition in particular, the above-described problem markedly occurs because the doughing time of such a composition tends to be long, so that it is strongly required to shorten the doughing time.